What are eye floaters made of?
Most eye floaters come from strands or clumps of collagen, a protein already present in the clear gel inside the eye. These tiny structures can cast shadows on the retina, which you see as drifting dots, threads or cobwebs. Less commonly, floaters contain blood, inflammatory cells or other material. Their appearance alone cannot tell you what they are made of.
What is the clear gel inside the eye made of?
The vitreous is the clear gel that fills the space between the lens and the retina, the light-sensitive lining at the back of the eye. It is about 99% water, but it behaves differently from a bag of plain water.
A very fine framework of collagen fibres, together with a water-binding substance called hyaluronan, gives the vitreous its gel-like consistency. Collagen is a protein; hyaluronan is a different kind of molecule. In a young, healthy vitreous, the arrangement of these components lets light pass through with little scattering.
The collagen is normal eye tissue. Having collagen in the vitreous does not itself mean that anything is wrong.
How do normal collagen fibres become floaters?
With age, parts of the gel become more liquid and its collagen framework changes. Some fibres gather into thicker bundles or clumps that interfere more with passing light. These are a common source of floaters.
Laboratory studies of human vitreous have found age-related changes on the surface of collagen fibres that can make them more likely to stick together. This helps explain the process, but it cannot predict when a particular person's floaters will appear or how troublesome they will become.
Floaters can develop before the gel separates from the retina. They may also become more noticeable during a posterior vitreous detachment, or PVD, when the back surface of the vitreous releases from the retina. These changes often occur earlier in short-sighted eyes.
The eye floaters guide explains how floaters are assessed and the options when they interfere with daily life.
Why do they look like dots, threads or cobwebs?
What you see is the effect of these structures on light reaching the retina, rather than a microscope image of the material itself. A strand can produce a thread-like shadow; a collection of strands can look like a cobweb. Its shape, density and position within the eye influence the appearance.
Floaters are often easier to notice against a bright, plain background, such as a white page or clear sky. They move as the vitreous shifts with eye movement and can continue drifting after the eye stops. This is why looking directly at one can seem to make it slip away.
A dark floater is not necessarily blood, and a pale one is not necessarily harmless. Similar-looking symptoms can have different causes.
What is a Weiss ring made of?
A Weiss ring is a ring-shaped opacity associated with separation of the vitreous from around the optic nerve head, where the optic nerve meets the retina. It includes tissue from that former attachment, particularly supporting cells known as glial cells, carried with the posterior vitreous surface.
It is not a loose piece of the seeing retina. A PVD and a retinal detachment are different conditions. However, the same vitreous separation can sometimes cause a retinal tear, so a new ring or other new floater still needs examination. Seeing a ring does not prove that the rest of the retina is safe.
Can floaters contain blood or inflammatory cells?
Yes. Floaters describe a visual symptom, rather than one particular substance. Material that should not normally be suspended in the clear vitreous can also interrupt light.
Blood: a leaking or torn blood vessel can release red blood cells into the vitreous. This can happen with a retinal tear, an injury or abnormal retinal blood vessels. The cause of the bleeding matters more than the shape of the spots.
Inflammatory material: white blood cells and inflammatory debris can cloud the vitreous during inflammation inside the eye, including some forms of uveitis. Inflammation may be associated with infection or other disease. Pain or redness may occur, but their absence does not establish that new floaters are harmless.
Other deposits: pigment cells may enter the vitreous with a retinal tear. Small calcium- and lipid-containing deposits, called asteroid bodies, are another type of vitreous opacity. Asteroid bodies are often found during an eye examination without causing troublesome symptoms.
These possibilities are reasons to examine the eye, not a way to diagnose yourself from a floater's colour or outline.
How does an eye examination tell the difference?
An ophthalmologist looks at the vitreous and retina through a dilated pupil. The examination can distinguish ordinary vitreous strands from signs of bleeding or inflammation and check for a retinal tear, including in the outer parts of the retina.
If blood or another opacity prevents a clear view, an ultrasound scan may help assess the back of the eye. A clear central retinal scan alone does not replace a careful examination for a peripheral tear.
The finding guides the next step. Stable collagen floaters may need observation, while bleeding, inflammation or a retinal tear may require treatment directed at their cause.
Does the material change the treatment options?
Yes, but symptoms and examination findings matter too. Mild, longstanding collagen floaters often need no treatment after the eye has been checked. If they remain intrusive, the potential benefit of intervention must be weighed against its risks.
YAG laser for floaters targets selected opacities; suitability depends on factors including their position and distance from the lens and retina. Vitrectomy removes vitreous containing the opacities. It is an operation with risks, including cataract, retinal detachment and infection, rather than a routine response to seeing a few spots.
The guide to recovery after floater vitrectomy explains what recovery involves. The short surgical video below shows vitreous being removed; it contains actual eye surgery.
Vitrectomy for floaters
Watch on YouTube →Are floaters dirt or dead cells?
Common age-related floaters are mainly changes in the eye's own collagen framework, rather than dirt that has entered the eye. Cells can contribute to some opacities, but describing all floaters as “dead cells” is inaccurate.
If a floater becomes less noticeable, has it dissolved?
Not necessarily. A floater may move away from the central line of sight, or the brain may become better at ignoring its shadow. Feeling less troubled by it does not prove that the material has dissolved. Persistent floaters can still be bothersome even when the retina is healthy.
When do floaters need urgent attention?
Seek urgent eye assessment the same day for sudden new floaters or a sudden increase, especially with flashes of light. A dark curtain or shadow, missing side vision or reduced vision needs immediate attention. New floaters with pain, redness or light sensitivity also need urgent assessment.
Contact an ophthalmologist promptly or attend an emergency department if you cannot obtain timely eye care. Do not wait for a routine appointment or try to identify the material yourself. A retinal tear can be painless. If symptoms change after an earlier reassuring examination, seek advice again.
Sources
- National Eye Institute. Floaters . Updated 4 December 2024.
- American Society of Retina Specialists. Posterior vitreous detachment .
- Silva AF, Alves MA, Oliveira MSN. Rheological behaviour of vitreous humour . Rheologica Acta. 2017;56:377–386.
- Bishop PN, Holmes DF, Kadler KE, McLeod D, Bos KJ. Age-related changes on the surface of vitreous collagen fibrils . Investigative Ophthalmology & Visual Science. 2004;45:1041–1046.
- Kahawita S, Simon S, Gilhotra J. Flashes and floaters: a practical approach to assessment and management . Australian Family Physician. 2014;43:201–203.
- National Eye Institute. Uveitis .
- American Academy of Ophthalmology. Posterior vitreous detachment . EyeWiki.
- Winkler J, Lünsdorf H. Ultrastructure and composition of asteroid bodies . Investigative Ophthalmology & Visual Science. 2001;42:902–907.